The present invention is directed to a discharge apparatus, particularly for controlling the discharge of molten material from a metallurgical vessel, and including structure for forming a refractory joint of predetermined thickness between a refractory nozzle and a refractory plate. More particularly, the present invention relates to structure incorporated into a sliding closure unit or slide gate of the type including a movable refractory plate, a movable mounting frame supporting the refractory plate, an exchangeable refractory nozzle, a mounting sleeve surrounding and supporting the nozzle, and a bayonet connection or similar lock between the sleeve and the frame for locking the sleeve and the nozzle to the frame in a position with an inner end face of the nozzle urged toward a confronting surface of the refractory plate, with a refractory joint forming a seal between the end face of the nozzle and the confronting surface of the refractory plate.
This general type of structure is known, for example as disclosed in DE-OS No. 27 27 742. In known such structures, when mounting an interchangeable nozzle in position on a movable refractory plate, the inner end of the nozzle acts directly on the movable refractory plate via a refractory joint, for example formed of refractory cement or mortar. As a result, the formation of the refractory joint depends solely on a manual assembly operation, and it is seldom that the joint is optimally formed. In most cases, over tightening occurs, with the result that the contact pressure between the movable refractory plate and a stationary refractory plate mounted in contact therewith increases beyond a predetermined value, and at least beyond acceptable values. Particularly, additional stresses occur in the area of the discharge opening through the movable refractory plate. These stresses, together with thermal stresses prevailing during operation of the sliding closure unit, deleteriously effect the smoothness of movement of the movable refractory plate and can result in destruction of such plate, thereby requiring replacement of the movable refractory plate after a relatively short period of time. On the other hand, at times it occurs that the compression of the refractory joint during mounting of a refractory nozzle is insufficient to form a satisfactory seal. This results in dangerous leakage of molten material during operation.